ENDEVCO 4418, Instruction Manual

DOCUMENT EDVIM4418 REVISION B 

Page 6 of 14 

3.1 Transducer 

Connection 

The transducer is connected to the 5 pin input socket.  A high accuracy voltage reference source 
provides power to the transducer.  When powered, the transducer will set a voltage at the inputs of 
the 4418 of approximately 5VDC

(dependent on the transducer and the offset).  The 4418 monitors 

this voltage to be within a pre-set range.  If the voltage is within the range the status indicator is 
turned Green and the system is ready to use.  If the voltage is out of range, the status indicator is 
turned Red – a fault condition exists.  

Note: Some transducers can take 1 – 2 minutes before 

the voltage settles into range. 

 Fig 

3. 

Pin Connections - as viewed from the front of the 4418 or the rear (wire side) of the mating input plug. 

3.2 Output 

Connection 

Measuring Instrumentation, e.g. data acquisition, data logger etc. should be connected to the output 
socket using coaxial cables.  Load impedance should be no lower than 100k

Ω

 to meet all 

specifications.  Ideally, the 4418 should be placed near the measuring instrumentation to minimize 
the effect of cable capacitance loading. 

3.3 Gain 

Setting 

Depressing the “Gain” switch cycles through the gain ranges of  x1, x10 and x100.  The gain range 
selected is shown by the indicator above the range being lit.  The gain together with the transducer 
sensitivity determines the acceleration range available from the system and the output sensitivity, 
e.g. for an accelerometer having a sensitivity of 10mV/g pk, and the maximum output of the 4418
being 10V pk:

Gain = 1 

Range = 1000g 

Output sensitivity = 10mV/g 

Gain = 10 

Range = 100g 

Output sensitivity = 100mV/g 

Gain = 100 

Range = 10g 

Output sensitivity = 1000mV/g 

3.4 Filter 

Selection 

A second order low pass filter is selected by depressing the filter switch.  This toggles the filter in 
and out.  With the indicator lit, the filter is selected IN.  The Standard filter provides attenuation of   
-3dB at 10 kHz. The filter maybe used to reduce the effects of HF noise and aliasing in data
acquisition systems.

3.5 

The Bridge Balance (Offset) 
The control, located on the rear panel, provides a means of adjusting the unbalanced output of the 
transducer for a zero measured output of the signal conditioner.  To adjust the Bridge Balance, first 
place the transducer in an axis which is not the primary sensitive axis, i.e. at 90 degrees. Monitor 
the output of the signal conditioner with a dc voltmeter.  With the power turned ON and after the 
recommended stabilization time, adjust the control for as close to zero volts as possible at the 
output.   

The 4418 utilizes low drift components in the design. However, small changes may be required after 
the initial setting.  When using the x100 gain, the adjustment of the control is very sensitive.  It is,  

Pin 1 – Excitation 

-

ve  (

Black

) 

Pin 2 – Signal 

-

ve  (

White

) 

Pin 3 – 

Cable Shield*

Pin 4 – Signal 

+

ve  (

Green

) 

Pin 5 – Excitation 

+ve

  (

Red

) 

*Pin 3 is connected to output signal ground.